The physics related to electromagnetic induction within an inductor and a transformer is described by Faraday's transformer equation:
  ɛ  =      -                  d        ⁢                                  ⁢        B            dt      
According to Moskowitz, “Permanent Magnet Design and Application Handbook” 1995, p 52, magnetic flux may be thought of as flux lines which always leave and enter the surfaces of ferromagnetic materials at right angles, which never can make true right-angle turns, which travel in straight or curved paths, which follow the shortest distance, and which follow the path of lowest reluctance. Hopkinson's Law (the magnetic analogy to Ohm's Law) shows that magnetic flux in magnetic circuits is analogous to electrical current in electrical circuits and reluctance in magnetic circuits is analogous to resistance in electric circuits.
Magnetic paths for transformers are often constructed of laminated ferrous materials and inductors often employ ferrite materials, which are used for higher frequency operation for both devices. High performance magnetic materials are now available for use as magnetic members comprising all or part of a flux path within a magnetic circuit and are well suited to accommodate the (rapid) switching of magnetic flux with a minimum of eddy currents.
The patent literature describes a number of constructs that have been devised to vary the amounts of magnetic flux in alternate flux paths to induce electricity by disproportionately dividing the flux from a stationary permanent magnet or magnets between or among alternate flux paths repeatedly for the purpose of generating electricity. The increase of flux in one magnetic path and the corresponding decrease in the other path(s) provide the basis for inducing electricity when coils are wound around the paths. A variety of flux switching means have been employed to cause the flux to be increased/decreased through a particular alternate path with a corresponding decrease/increase in the other path and to do so repeatedly.
A “reluctance switch” is a device that can significantly increase or decrease the reluctance (resistance to magnetic flux) of a magnetic path in a direct and rapid manner and subsequently restore it to its original value in a direct and rapid manner. A reluctance switch typically has analogue characteristics. By way of contrast, an off/on electric switch typically has a digital characteristic as there is no electricity bleed-through. With the current state of the art, reluctance switches often have flux bleed-through. Reluctance switches may be implemented mechanically, such as to cause keeper movement to create an air gap, or electrically utilizing various techniques. One electrical approach, for example, uses control coils wound around a flux path. Another electrical arrangement involves the placement, within a flux path, of certain combinations of materials that change their reluctance upon the application of electricity.
A reluctance switch may also be implemented by using electromagnetic induction to magnetically saturate a section of the magnetic path to create a region of high reluctance (on-condition to an off-condition). A reluctance switch may also be implemented by using electromagnetic induction to magnetically un-saturate a section of the magnetic path that is already saturated by the use of a permanent magnet (off-condition to an on-condition). In both cases, the reluctance switch design must be sufficiently novel so as to not direct the electromagnetically induced flux used to operate the switch into the rest of magnetic circuit. A reluctance switch also may be implemented by temporarily disrupting a magnetic flux bridge (on-condition to an off-condition) such as that provided by a ferrofluid.
Villasenor de Rivas U.S. Pat. No. 4,006,401 discloses a method and apparatus for the production of electricity through the operation of a magnetic circuit that uses a single stationary permanent magnet, a single flux path around which is wound one or more conducting coils, and four reluctance switches that, when operated in the prescribed 2×2 alternating sequence, could alternately switch the flux from the permanent magnet through the single flux path so as to cause a reversal of the polarity (direction) in the path and thereby induce alternating electrical current in the coils. The method and apparatus provide a single flux path and operate its switching so as to cause a reversal of the polarity (direction) in the path.
Flynn U.S. Pat. No. 6,246,561; Patrick, et al. U.S. Pat. No. 6,362,718; and Pedersen U.S. Pat. No. 6,946,938 all disclose a method and apparatus for switching (dividing) the quantity of magnetic flux from a stationary permanent magnet or magnets between and among alternate paths for the purpose of generating electricity (and/or motive force). They provide for the increase of magnetic flux in one path with a corresponding decrease in the other path. There are always at least two paths.
Published U.S Patent Application No. 2009/0096219 discloses a method and apparatus for the production of electricity through the operation of a magnetic circuit that uses two single stationary permanent magnets, a single flux path around which is wound one or more conducting coils, and four reluctance switches that, when operated in the prescribed 2×2 alternating sequence, alternately switch the flux from the permanent magnet through the single flux path so as to cause a reversal of the polarity (direction) in the path and thereby induce alternating electrical current in the coils. The reluctance switches use magnetic saturation to change (increase) reluctance.
Veneruso US Patent 20100164303 A1 discloses the use of ferrofluids to reduce reluctance in an electrical generator.